Public address unit



FIG. 1 is a front elevational view of a public address unit showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a right-side elevational view thereof;

FIG. 4 is a left-side elevational view thereof;

FIG. 5 is a rear elevational view thereof; and

FIG. 6 is a bottom plan view. 

The ornamental design for a public address unit, as shown. 